In #268 I've made a stab at investigating the differences between LaTeX and KaTeX. Many of these differences should probably considered bugs, but some are intentional. Examples include the possibiluty of using sizing commands in math mode, the additional color commands, and of course the KaTeX package.

Should we create a package called katex.sty for LaTeX, which contains all these deviations? The goal would be allowing the same set of formulas to render as similar as possible in both environments.